Air conditioning system



Sept. 12, 1939. h M. PARCARO 2,172,377

AIR CONDITIONING SYSTEM Filed Feb. 25, 1937 2 Sheets-Sheet 1 w & l

IN VENTOR. M/CHA 1 PA ECAEO A TTORNEYS.

Sept. 12, 1939. v PARCARO 2,172,877

AIR CONDITIONING SYSTEM Filed Feb. 25, 1937 2 Sheets-Sheet 2 INVENTOR.

M/CHAEL p/IZCAFO Z/MMQLQ A TTORNEYS.

Patented Sept; 12, 1939 UNITED. STATES AIR CONDITIONING SYSTEM MichaelPal-care, Bloomfield, N. J.,

assigmor to Carrier Corporation, Newark, N. J., a corporation ofDelaware Application February 25,

Claims.

This invention relates to air conditioning and is a continuation in partof applicants copending application Serial No. 71,837, filed March 31;

It is well known that one way of reducing the moisture content of air isto cool the air below its dewpoint. Air which has been dehumidified inthis way is relatively cold,and therefore it is generally necessary toreheat such air before introducing it into enclosures which are to beconditioned. This is especially true where the conditioned enclosuresare intended for human occupancy. One method of effecting such reheatinghas been to pass the cold and dehumidifled air in heat exchange relationwith heaters supplied with steam or similar heating medium. This methodof reheating, while it is adapted to produce desired conditions when theoperation is suitably controlled and regulated, is relatively expensivesince it embraces removing heat from air at considerable cost and thensupplying heat to the same air at an additional and considerable cost. a

The general object of the invention is to provide an improved method ofand means for reheating air which has been dehumidified by reduction ofits temperature below its dewpoint.

It is well known thatthe temperature of compressed refrigerant gasleaving a refrigerant compressor is relatively high. While inconventional systems the heat of such compressed refrigerant gas isdissipated to the condensing medium, applicant employs the heat ofcompressed refrigerant gas to effect reheating of air which has beendehumidified by the evaporation of the refrigerant.

Accordingly, it is another object of the invention to dehumidify air bycooling the air to a temperature below its dewpoint by evaporating avolatile refrigerant in heat exchange relation therewith, to compressthe evaporated refrigerant, whereby its temperature is increased, and totransfer heat from the compressed refrigerant gas to the colddehumidified air, whereby said air is reheated and its relative humidityreduced.

It is another object of the invention to dehumidify a volume of air bycooling the air below its dewpoint and to reheat said dehumidified airby. mixing-therewith another volume of air which has been heated.

It is another object of the invention to dehumidify a volume of air bycooling the air below its dewpoint, and to reheat said dehumidified airby mixing therewith another volume of air which has been heated bycompressed refrigerant 1937, Serial No. 127,695 (01. 62-6) gasevaporated by heat exchange with said dehumidified air.

Another object of the invention is to provide an improved system forreheating air dehumidified by mechanical refrigeration which is,relatively 5 simple, which is inexpensive to install and operate, andwhichis adapted greatly to reduce the cost of reheating as heretoforepracticed.

A feature of the invention resides in conditioning an enclosure bydrawing air from the enclo- 10 sure and/or the outdoor atmosphere,evaporating a volatile refrigerant in heat exchange relation with saidair to cool said air below its dewpoint, whereby moisture isprecipitated therefrom, drawing other air from the enclosure 15 and/orthe outdoor atmosphere, compressing the evaporated refrigerant,circulating said compressed refrigerant gas in heat exchange relationwith said other air, mixing said other air and said dehumidified air andsupplying said air 'mixture to said enclosure.

Another feature of the invention resides in controlling the relativeproportions of dehumidified air and heated air supplied to the enclosurein accordance with changes in either temperature 25 or humidity at anydesired point in the air circulating system.

Another feature of the invention resides in controlling the relativeproportions of dehumidified air and heated air supplied to the enclosure30 in accordance with changes in either tempera.- ture or humidity atany desired point in the air circulating system, and controlling thedehumidifying action in accordance with. changes in either temperatureorrelative humidity at any desired 35 point in the air circulating system.

Another feature of the invention resides in the provision of meansincluding a refrigerant evaporator for dehumidifying a volume of air,means for supplying other air to be mixed with said dehumidified air, aheating coil in heat exchange relation with said other air, a compressorfor compressing the evaporated refrigerant, and means for supplying saidcompressed refrigerant to said heating coil and then to a condenserwhere it is liquefied prior to a repetition of the refrigerating cycle.

Another feature of the invention resides in the provision of arefrigerating system including an evaporator, a compressor and acondenser for 5 dehumidifying air, means for supplying other air to bemixed with said dehumidified air, a heater for heating said other airprior to mixture with said dehumidified air and means for routingrefrigerant gas from said compressor through air whenever the load onsaid heater and then through said condenser or directly to saidcondenser.

Another feature of the invention resides in dehumidifying air by theevaporation of a volatile 5 refrigerant, compressing the evaporatedrefrig- 15 invention will be more apparent from the following'description to be read in connection with the accompanying drawings, inwhich- Fig. 1 diagrammatically represents an air conditioning system inaccordance with the invention. 20 Fig. Zrepresents a modification of thesystem of Fig. 1, in which compressed refrigerant gas is adapted to becirciilated directly to the condenser,

or to the reheater and then through .the con- 25 denser.

Fig. 3 is a modification of the invention adapted to supply hotrefrigerant gas to the heater when the load on the refrigerantcompressor falls below a predetermined point.

and.

Fig. 5 diagrammatically illustrates an alternative duct arrangement forsupplying air to be mixed with the dehumidified air.

Referring to the drawings, similar designations referring to similarparts, numeral l designates an enclosure conditioned by air suppliedthereto through duct ll under the influence of fan l2. Air is withdrawnfrom the enclosure l0 through 40 duct l3 and is supplied to airconditioning casing ll. Preferably, duct 13 connects to the outdooratmosphere through a duct l so that outdoor air as well as return airfrom the enclosure l0 may be supplied to the air conditioning casing II.It

5 is preferred to provide dampers IS in the duct l5 and dampers l1 inthe duct IS, the dampers i6 and I1 being differentially connected, tocontrol the relative proportions of outdoor air and return air suppliedto the conditioning casing through 50 duct l3. Control of the dampers i6and 11 may be effected manually or automatically, as desired, but it ispreferred that at least a small quantity of outdoor air be supplied tothe conditioner casing H at all times. Within the conditioner cas- 55ing I4 is provided a dehumidifying coil l8 supplied with liquidrefrigerant through supply line 19 leading from refrigerant condenser20. Air supplied to the conditioner casing it through duct i3 contactsthe coils l8 and is thereby de- 60 humidified. The precipitated moisturemay be drained from the bottom" of the casing l4 in any desired manner.

A duct 2i connects duct I3 with the conditioner casing I4 at a pointbeyond the coils Hi. The

5 duct 2| constitutes a bypass for supplying room air to the conditionerto be'mixed with the air dehumidified by coils l8 before thedehumidified air is supplied to the enclosure. If desired, duct 2| maybe connected to the outdoor atmosphere 70 through a connection similarto duct l5, and in such case it is preferred to provide dampers cor-.

responding to dampers l6 and I1 associated with duct i3.

As will be understood, the dry bulb temperature of the dehumidifled airis relatively low, and it is Fig. 4 isa modification of the system ofFig. 3,

avast":

generally desirable that this air be reheated to a substantial degreebefore it is supplied to the enclosureto be conditioned. To effect suchreheating applicant provides a heater 22 in duct 2|, which is suppliedwith hot refrigerant gas discharged by compressor 23 through line 24.The heat of the hot compressed refrigerant gas is partially removed byair circulating through duct 21 and this air is accordingly reheated,and hence reheats the dehumidifled air upon its mixture therewith inmixing chamber 25 of the conditioner casing. It will thus be observedthat reheating of the dehumidified air is accomplished without resort tothe use of steam reheaters or the like, which, as is well known, areexceedingly expensive to operate.

A preferred form of the invention includes dampers or the like, forregulating the relative proportions of dehumidifled air and heated airsupplied to the mixing chamber 25. Such dampers may be of any desireddesign but should be differentially connected or arranged, so that whenthe supply of air to the mixing chamber from one source is decreased,the supply of air from the other source will be increased and viceversa. As illustrated, dampers 26 will operate in this manner since whenthe dampers are opened to provide a greater supply of dehumidifled airto the mixing chamber 25, the supply of heated air to the mixing chamberis reduced; and conversely, when the dampers 26 are closed somewhat toreduce the supply of dehumidified air, the supply of heated air isincreased. Dampers 26 may be controlled manually, if desired, but in apreferred form of the invention they are automatically controlledresponsive to variations in either temperature or humidity at anydesired point in the air circulating system. In some applications it maybe desired to position the control element 21 in the'supply duct H, asshown in Fig. 1. However, the control element may be positioned at anydesired point in the enclosure, in the return duct or within the airconditioning casing it without departing from the scope of theinvention. The control element 21 may be either a hygrostat or athermostat controlling the dampers 26 through damper motor 28 of anydesired type. Similarly, the dehumidifying action may be also.controlled manually or automatically, but

automatic control is preferred, and in a preferred form of the inventionthe supply of refrigerant to the coil I8 is controlled by a valve 29,which is regulated by a control element 30. Control element 30 may beeither a hygrostat or a thermostat and, as described in connection withcontrol element 21, may be' located at any desired point in the aircirculating system. As illustrated in Fig. 1, control element 30 islocated in the air supply duct ll. When the control element 21 is athermostat the control element 30 is a hygrostat, and when the controlelement 21 is a hygrostat the control element 30 is a thermostat.

In Fig. 2 is illustrated a modification of the system of. Fig. 1,wherein line 3i connects compressed gas line 24 with the inlet tocondenser 20 in a course by-passing heater 22. A valve 32 is adapted tosupply compressed refrigerant gas delivered from the compressor toeither the heater 22 and thence to condenser 20, or directly tocondenser 20 through line 3|. A check valve 32 is provided in line 34,connecting heater 22 and condenser 20, to permit fluid flow from theheater-to the condenser and to prevent fluid flow in a reversedirection. By means of this arrange- I ment compressed refrigerant gasmay be supplied 15 plied to condenser 29 heating of the dehumidified airis desired. The

valve 32 is preferably of the three-way type, well known in the art andtherefore requiring no detailed description here, but, if desired, itmay be replaced by other suitable fiow control means. For example, ashut-off valve in the line 3| and a shut-off valve in the line 24,beyond the junction point of lines 24 and 3|, might be used to effectthe same results as are provided by valve 32.

Fig. 3 illustrates a modification of the invention in which amulti-cylinder compressor is used, and in which refrigerant gas is usedfor heating purposes only when the load on the compressor falls below apredetermined point. Suction line 35 supplies evaporated refrigerant tocylinders 23a and 23b of compressor 23 and refrigerant gas dischargedfrom the compressor may be supthrough line 36. Line 24a communicateswith discharge connection 3'! of compressor cylinder 23b. A cut-outvalve 38 in line 24a is under the control of control element 39 whichresponds to changes in conditions in the gas suction line or in theenclosure conditioned by the system. Control element 39 may be athermostat or apressurestat or similar de-- vice and is operative'toopen the valve 38 whenever the load on the compressor falls below apredetermined point. A check valve 40 permits flow from compressorelement 23b to line 36 but prevents how in. a reverse direction. A.similar system is disclosed in applicants copending application SerialNo. 71,837, filed March 31, 1936, for recirculating gas through thecompressor whenever the load on the compressor falls below apredetermined point and, as disclosed in said copending application, athree-way valve at the junction of lines 31 and 24a may be substituted,if desired, for the valve 38 and the check valve 49, such three-wayvalve being regulated by control element 39. In a preferred embodimentof the invention the line 24a. is provided with a connection 4| to' theintake side of the compressor and a valve 42 is used to routerefrigerant as to either heater 22 or to the intake of compre'ssor 23through line 4.|. A check valve 43 is provided in gas line 44 to permitflow fromthe heater 22 to the inlet ofcondenser 20 and to prevent fluidflow in a reverse direction.

If desired, valve 42 may be manually adjusted or may be controlledautomatically by a temperatureor humidity-responsive device 45 locatedat any desired point in the system.

In the arrangement of Fig. 4, gas discharged from compressor element 23bmay be supplied directly to condenser 29 through line 36 or to heater 22through line 24a and thence to condenser 20 through line 44, the routingof the compressedrefrigerant gas being controlled by valve 46, which maybe controlled manually or automatically, as desired. A check valve 41permits flow from the heater 22 to the inlet of condenser 29 butprevents flow in a reverse direction. It will be noted that thearrangement of Fig. 4 is similar to the arrangement of Fig. 2, exceptthat in Fig. 4 at least. one of the compressor elements dischargesdirectly to the condenser at all times,

whereas in the arrangement of Fig. 2, all of the gas discharged from thecompressor may be routed through the heater 22, and then to thecondenser 29.

In connection with Figs. 3 and 4, it is to be understood that while onlytwo compressor elements have been illustrated, the arrangement may beextended to apparatus embracing three,

or more cylinders. In such case, two or more compressor elements orcylinders wouldbe arranged to supply compressed refrigerant gas to theheater.

In the various forms of the invention above described, substantially allof the by-passed air circulated through duct 2| contacts with heater 22.Fig. 5 illustrates an arrangement in which a portion only of theby-passed air is passed in contact with the heater 22, the remainder ofthe air circulated through by-pass duct 2| being by-- passed around-theheater 22. Preferably, a partition 48 is provided in the duct to providetwo air passages, designated 49 and 50, therein. Duct section 49, asillustrated, contains the heater 22. Duct sections 49 and 50 areprovided with differentially connected dampers 5| and 52 so that as airflow through one of the duct sections is increased, air flow through theother duct section will be decreased, and vice versa. The dampers 5| and52 may be adjusted manually, if. desired, but preferably they areautomatically controlled. The adjustment of the dampers 5| and 52 may becontrolled by a thermostat or hygrostat located at any desired point inthe system,

as described in connection with control element 21. Such temperatureorhumidity-responsive control of the dampers 5| and 52 is preferably usedin conjunction with the automatic control of dampers 26 as abovedescribed.

While the heater 22, to which hot refrigerant gas is supplied, Has beendescribed as being positioned within the duct 2| and adapted to becontacted directly by the air passing through this duct, it will beapparent to those skilled in the art that the heater 22 might be locatedwithout theduct 2| and utilized for the purpose of heating water orother suitable medium which might then be routed through a surface-typeheat exchanger located within the'duct 2|. Similarly, the evaporatorcoils, while they have been described as being-within the airconditioning cas ing, might be used to cool a conditioning medium,

such as brine, instead of directly cooling the ditioner casing.Accordingly, in the claims the expression heat exchange relation shallbe understood to refer to both direct and indirect heat exchange.

Since many modifications may be made in the invention without departingfrom its scope, applicant intends that the above description andaccompanying drawings be considered as' illustrative only, applicantlimiting himself only as indicated in the appended claims.

I claim:

1. In an apparatus of the character described,

an evaporator, a compressor, a condenser, means for passing a firstvolpme of air in heat exchange relation with said evaporator wherebysaid first volume of air is dehumidified, means for supplying to andmixing with said first volume of dehumidified air a second volume ofair, a heater arranged in heat exchange relation with said second volumeof airand adapted to heat said second volume of air prior to mixturewith said first volume of dehumidified air, said heater being connectedbetween the outlet of said compressor and the inlet of said condenser,and means for supplying compressed refrigerant gas to said heaterresponsive to falling of the pressure at the inlet to said compressorbelow a predetermined point and for supplying compressed refrigerant gasto said condenser in a course by-passing said heater responsive torising of the pressure at the inlet to said compressor above said point.

2. In an apparatus for conditioning air under summer operatingconditions, means for withdrawing air from the enclosure, meansincluding a refrigerant evaporator for dehumidifying a portion of saidwithdrawn air, means for supplying liquid refrigerant to saidevaporator, compressor apparatus for withdrawing refrigerant gas fromsaid evaporator and for compressing said refrigerant gas, means forpassing said compressed refrigerant gas in heat exchange relation withanother portion of said air withdrawn from the enclosure responsive todecreases of the load on said compressor apparatus below a predeterminedpoint, means for mixing said portions of the air withdrawn from theenclosure, means for supplying the resultant air mixture to saidenclosure, and means for controlling the relative proportions of saiddifferent air portionsin said result-,

accordance with variations in a condition of ir at a point in thesystem.

3. In an apparatus of the character described, an evaporator, acompressor comprising a plurality of compressing elements, a condenser,means for passing air in heat exchange relation with said evaporatorwhereby said air is dehumidified, means including a heater adapted tosupply heat to said air subsequent to dehumidification thereof, meansfor routing compressed refrigerant from at least one bf said compressingant mixture 1 elements constantly and at all times during operation ofthe apparatus directly to said condenser in a course by-passing saidheater, means for routing compressed refrigerant gas from at leastanother of said compressing elements through said heater and thence tosaid condenser in response to a decrease of the load on said compressorbelow a predetermined point, and for routing refrigerant gas from saidlast-mentioned compressing element directly to said condenser in acourse by-passing said heater in response to an increase of the load onsaid compressor above a predetermined point.

4. Inv an apparatus of the character described,

a refrigerant evaporator, a compressor compris-- ing a plurality ofcompressing elements, a condenser, means for passing a first volume ofair in heat exchange relation with said evaporator whereby to effectdehumidiflcation of said first volume of air, means for supplying to andmixing with said first volume of dehumidified air a second volume ofair, a heater arranged in heat exchange relation with said second volumeof air adapted to heat said second volume of air prior to mixture ofsaid second air volume with said first air volume, means for routingcompressed refrigerant from at least one of said compre'sslng elementsconstantly and at all times during operation of the apparatus directlyto said condenser in a course by-passing said heater, means for routingcompressed refrigerant gas from at least another of said compressingelements through said heater and thence to said condenser whenever theload on said compressor 'falls below a predetermined point, and forrouting refrigerant gas from said last-mentioned compressing elementdirectly to said condenser in a course bypassing said heater wheneverthe load on said compressor exceeds a predetermined point.

5. In an apparatus of the character described,

an evaporator, a compressor, a condenser, means for passing a firstvolume of air in heat exchange relation with said evaporator wherebysaid first volume of air is dehumidified, means for supplying to 'andmixing with said first volume of dehumidified air a second volume ofair, a heater arranged in heat exchange relation with said second volumeof air and adapted to heat said second volume of air prior to mixture ofsaid second air volume with said first air volume, said heater beingconnected between the outlet of said compressor and the inlet of saidcondenser, and means for supplying compressed refrigerant gas to saidheater responsive to a decrease in the temperature at the inlet to saidcompressor below a predetermined point and for supplying compressedrefrigerant gas to said condenser in a course by-passing said heater inresponse to an increase in the temperature at the inlet to saidcompressor above said point.

6. In an apparatus of the character described, an evaporator, acompressor, a condenser; means for passing air in heat exchange relationwith said evaporator whereby said air is dehumidified, a heater adaptedto supply heat to said air subsequent to the dehumidification thereof,said I heater being connected between the outlet of said compressor andthe inlet of said condenser, a control element responsive to changes inthe condition of refrigerant gas supplied to said compressor, and meansunder the control of said control element for selectively routingcompressed gas from said compressor directly to said condenser orthrough said heater and thence to said condenser.

7. In an apparatus of the character described, a refrigerant evaporator,a compressor comprising a plurality of compressing elements, acondenser, means for passing a first volume of air in heat exchangerelation with said evaporator whereby to effect dehumidification of saidfirst volume of air, means for supplying to and mixing with said firstvolume of dehurnidified air a second volume of air, a heater arranged inheat exchange relation with said second volume of air adapted to heatsaid second volume of air prior to mixture thereof with said first airvolume, means for routing compressed refrigerant from at least one ofsaid compressing elements constantly and at all times during operationof the apparatus directlyto said condenser in a course by-passing saidheater, and means for selectively routing compressed refrigerant gasfrom at least another of said compressing elements either through saidheater and thence to said condenser, or directly 'to said condenser in acourse by-passing said heater.

1}. In an apparatus of the character described, a refrigerantevaporator, a compressor comprising a plurality of compressing elements,a condenser, means for passing a first volume of air in heat exchangerelation with said evaporator whereby to effect dehumidification ofsaidfirst volume of air, means for supplying to and mixing with saidfirst volume of dehumidified air a second volume of air, a heaterarranged in heat an evaporator, a compressor, a condenser, means anotherof said compressing elements either through said heater and thence tosaid condenser, or directly to said condenser in a course bypassing saidheater, said last-mentioned means including control means actuatedin'response to changes in a condition of refrigerant delivered to saidcompressor.

9. In an apparatus of the character described,

for passing a first volume of air in heat exchange relation with saidevaporator whereby said first volume of air is dehumidified, means forsupplyinganother volume of air for mixture with said first volume of airsubsequent to dehumldification of said first volume of air, a heateradapted to heat said other volume of air subsequent to mixture thereofwith said first volume of air, said heater being connected between theoutlet of said compressor and the inlet of said condenser, a controlelement responsive to changes in a condition of. refrigerant gassupplied to said compressor, andmeans under the control of said controlelement for selectively routing compressed gas from said compressordirectly to said condenser or through said heater and thence to saidcondenser.

10. In an apparatus of the character described, a refrigerantevaporator, a compressor comprising a plurality of compressing elements,a condenser, means for passing air in heat exchange relation with saidevaporator whereby to efiect dehumidification thereof, a heater adaptedto supply heat to said air subsequent to dehumidification thereof, meansfor routing compressed refrigerant from at least one of said compressingelements constantly and at all times during operation of theapparatus'directly to said condenser in a course by-passing said heater,and

means for routing selectively compressed refrigerant gas from at leastanother of said elements, whenever the load on said compressor is belowa predetermined point, either to 'the inlet of said compressor or tosaid heater, and means for delivering compressed refrigerant gas fromsaid last-mentioned compressor element directly to said condenser whenthe load on said compressor exceeds a predetermined point.

MICHAEL PARCARO.

